Ocular biomechanical properties measuring and monitoring device

The present invention relates to a device, a kit, a system and a method for measuring and monitoring a plurality of ocular biomechanical properties (OBP). The present invention relates in particular to a device that can be placed on the eye of a user to monitor a plurality of ocular biomechanical properties over an extended period of time, for example 8 hours, 12 hours, 24 hours or more.

Glaucoma is a widespread disease characterized by an elevated intraocular pressure (IOP). This elevated IOP produces a gradual loss of peripheral vision. There is therefore a need to have a detailed knowledge of IOP as well as other related ocular biomechanical properties (OBP) in glaucoma patients in order to provide reliable diagnostics or for setting up new therapies.

There have been provided several solutions for measuring IOP in glaucoma patient. Some solutions use direct pressure sensor which require a rigid contact lens to directly detect the intraocular pressure, some other solutions measure different parameters such as the eye's dimensional variation through the use of different types of strain gauges which require a soft contact lens. Each of these solutions being limited to the fact that they measure a single parameter. Therefore, when several parameters are required, several measurement sessions are needed. Given that a measurement preferably lasts for at least 24 hours, this can be very uncomfortable for the patient.

For example, inventors found that the relationship between different OBPs, such as, but not limited to IOP and temperature or/and even optionally dimensional variation of the eye permits the calculation of a new biomarker. Furthermore, despite IOP is the only modifiable risk factor, recent publications highlighted the valuable role of another OBP, the ocular volume change (OVC), as valuable information in relation to the disease pathogenesis. Such OBP will define a new biomarker as result of the ocular volumetric response to a pressure input in a corresponding time frame. IOP and OVC have been considered until now separately as there is no device able to detect simultaneously variation in pressure and corresponding variation in volume monitoring continuously.

A primary object of the present invention is therefore to provide for a device and a method capable of measuring two different OBPs, such as but clearly not limited to direct IOP, temperature and optionally eye's dimensional variation simultaneously, because the measurement conditions can vary from one measurement to the other one, so inventors have explored for a new device for simultaneously or consecutively measuring and monitoring two OBPs.

In the present application the term simultaneously means that the measured OBPs are measured during the same time interval regardless of the exact arrival time of each signal to the recording device. Even if there is a slight time phase between the two signals (few seconds or less) simultaneously means that the OBPs are measured during a single measurement period of time. On the other hand, the term consecutively means measuring a first OBP alone and then, without replacing the measuring and monitoring device, measuring a second OBP once the first measurement is completed.

In the present invention, ocular biomechanical properties (OBP) relate to parameters/properties such as intraocular pressure (IOP), intraocular volume (IOV), corneal rigidity, corneal thickness, sclera rigidity, geometrical dimensions and/or temperature of the eye and more generally any ocular property even non-biomechanical like a specific concentration.

A particular OBP, the Ocular Compliance (OC) measures the ability of an eye to increase its volume in case of an intraocular pressure increase. The value of OC can be defined as:

Since the viscoelastic properties of the eye tissues create a pressure relaxation which tends to reduce the intraocular pressure (IOP) over time at a constant intraocular volume (10V), this is not a constant value but the slope at a given time of the Volume vs Pressure relationship.

In this regard, another object of the invention is to solve the above-mentioned problems and more particularly to provide a pressure sensitive device accurately measuring IOP and eye's dimensional variation simultaneously over a large period of time while allowing data transmission wirelessly.

However another challenge which has been faced by the inventors relates to the difficulty in designing a device capable of measuring IOP and OVC since these two OBP are measured in different manner and requires different stiffness environment such that such a device requires both hard and soft contact lens portions.

Therefore, another object of the invention is to provide a new contact lens-like OBP sensitive device providing the advantages of both the hard and soft contact lenses without their drawbacks.

Another object of the invention is to provide a new contact lens-like OBP sensitive device providing at least one new biomarker based on the relation between the IOP and the eye's dimensional variation.

The above problems are solved by the present invention.

A first aspect of the invention is an OBP measuring and monitoring device comprising a contact lens presenting an inner surface and an outer surface and a sensing unit, said sensing unit being united with said contact lens such that it is applied against an eye of a user for sensing at least a first OBP and a second OBP of said eye when said contact lens is worn by said user, said sensing unit being adapted to measure simultaneously or consecutively the first and second OBPs and transmit these OBPs to a CPU such that said CPU receiving said measurement is able to determine at least one new biomarker based on a combination between at least these two OBPs.

Preferably, the sensing unit comprises a single sensor capable of measuring at least two different OBPs. Therefore, the lens is less cumbersome.

Alternatively the sensing unit comprises at least two single sensors each capable of measuring a single OBP. In this manner, the measurements can be made simultaneously.

Preferably, the at least two single sensors are each capable of measuring a single OBP different from each other.

According to a preferred embodiment, the first OBP is the intraocular pressure and the second OBP is the eye's temperature. In this manner, more precise IOP as a new biomarker can be measured.

Alternatively, the first OBP is the intraocular pressure and the second OBP is the eye's dimensional variation. In this manner, a new biomarker can be measured.

Advantageously, the sensing unit comprises an eye's dimensional variation sensor as an active strain gauge presenting a circular or arc shape and is situated in an outer portion around an inner portion of said soft contact lens. The strain gauge can therefore easily sense the soft contact lens deformation.

Preferably, the eye's dimensional variation sensor comprises several active strain gauges.

According to a preferred embodiment, said strain gauge is made of a resistive material, such as a metal or an alloy.

Preferably, said strain gauge is a continuous longitudinal element.

Advantageously, the eye's dimensional variation sensor comprises four gauges in a Wheatstone bridge configuration, such as two active gauges and two passive ones being placed alternatively on the bridge. This permits to compensate for the temperature deviation and to double sensitivity.

According to a preferred embodiment, the sensing unit comprises a direct pressure sensor.

Preferably, the contact lens is a soft contact lens comprising an inner portion and an outer portion, said inner portion being more rigid than said outer portion. In this manner, the surface in contact with the eye is the soft contact lens and both pressure sensor and the more rigid portion are encapsulated within that contact lens.

According to a preferred embodiment, the direct pressure sensor is located in said inner portion. As a result of this proposed composite structure using materials of different rigidity, the pressure sensor can therefore accurately measure the IOP.

Advantageously, the inner portion is adapted to at least partially rigidify a central portion of the inner surface of said contact lens so as to maintain said rigidified inner surface with a curvature radius adapted to flatten at least a portion of the eye surface in contact with the direct pressure sensor so as to reach a pressure equilibrium around the direct pressure sensor when said contact lens is worn by said user.

Advantageously, the inner portion has a general shape similar to a meniscus lens. In this manner, it has the same general shape as the contact lens and more closely fits to the eye general shape.

Preferably, the inner portion is smaller in dimension compared to the outer portion and is centered in the contact lens. Thus, it can be more easily placed inside the contact lens since the center part of the contact lens is thicker.

According to a preferred embodiment, the inner portion comprises a rigid insert.

Preferably, the rigid insert comprises a plurality of through holes. In this manner, it prevents hypoxia of the eye through the rigid insert and it also permits securing the rigid insert within the contact lens.

Advantageously, the rigid insert is made of a material chosen in the group of polymers, biopolymers, ceramics, glasses, metals and RGP.

Preferably, the outer portion of said contact lens is made of a material chosen in the group of hydrogels, silicone-hydrogels and silicones.

Advantageously, any one of the inner portion and the outer portion of said contact lens is made of a material having a tunable stiffness or a stiffness gradient.

Preferably, the pressure sensor is in direct contact with the eye of the user when the user is wearing the contact lens. In this manner, a favorable contact is established between the pressure sensor and the measurement interface so as to improve the sensitivity.

Alternatively, the pressure sensor is in indirect contact with the eye of the user when the user is wearing the contact lens. Thus, the pressure sensor is protected from the direct contact to the eye surface in order to improve comfort.

According to a preferred embodiment, the pressure sensor is located within a cavity formed in an inner concave side of the rigid insert, and wherein the cavity is filled with a pressure transmitting filler material that covers the pressure sensor such that a layer of the filler material is located between the pressure sensor and the inner surface of the contact lens when the user is wearing the contact lens. In this manner, the pressure sensor is not in direct contact with the rigid insert.

Preferably, the filler material is a material softer than the inner portion. Thus, allowing a perfect mechanical insulation of the pressure sensor.

Alternatively, the filler material is softer than the material of the outer portion. In this manner, radial forces transmitted by the soft material of the contact lens are without influence or attenuation on the pressure sensor.

Alternatively, the filler material is the same material as the material of the outer portion. In this manner, the device is more easily manufactured.

Preferably, the cavity is formed in the center of the inner portion. Thus, it is provided on the thicker portion of the contact lens.

Advantageously, the inner surface of the contact lens beneath the cavity presents a softer surface than the rest of the inner surface beneath the inner portion. In this manner, the IOP is transmitted with a lowered attenuation.

Alternatively, the inner surface of the contact lens beneath the cavity presents a surface softness similar than the rest of the inner surface beneath the inner portion. Thus, achieving the mechanical insulation from the rigid insert without material discontinuity between the pressure sensor and the eye.

According to a preferred embodiment, the contact lens further comprises an antenna and a microprocessor for telemetry powering and data transfer. In this manner, this permits wireless transfer of data.

Preferably, the sensing unit comprises a plurality of OBP sensors adapted to measure the same OBP. In this manner, accuracy of the measurement can be improved through aggregation of the results.

Furthermore, the OBP measuring and monitoring device of the invention doesn't need to be customized for each user, because it can be adapted to a large number of patients by having several sizes available that only differ in their external shape so as to easily adapt to different eye shapes and sizes. The OBP measuring and monitoring device can also be worn over a long period of time without discomfort for the user.

A second aspect of the invention relates to a kit comprising an OBP measuring and monitoring device of the first aspect of the invention, and a portable recording device configured for communicating with the OBP measuring and monitoring device and for storing data received from the OBP measuring and monitoring device. The particular advantages of this kit of the invention being similar to the ones of the device of the first aspect of the invention, they will not be repeated here.